1. Field of the Invention
This invention relates to an apparatus for retrieving downhole devices in a wellbore. More particularly, but not by way of limitation, the invention relates to retrieving downhole devices when the workstring utilized does not provide for a rotational movement such as when the workstring is coiled tubing, wireline, or electric line.
2. Description of the Prior Art
Wireline set, tubing retrievable packer type bridge plugs are known in the art. In oil and gas wells, it is desirable to have a bridge plug which will withstand high differential fluid pressures thereacross. In the past, these bridge plugs have been set utilizing either wireline or drill pipe workstrings. Examples of these wireline set tubing retrievable bridge plugs are found in Fore and Caskey U.S. Pat. No. 4,648,446, and Caskey U.S. Pat. No. 4,693,309, both patents being assigned to the assignee of the present invention. Both of the disclosures having been referred to are incorporated by express reference hereto.
As will be seen from these patents, the apparatus used to retrieve these packers comprises an overshot member, upper ring spring holder, lower ring spring holder, and ring spring. Furthermore, to retrieve the bridge plug in the prior art, the retrieving tool previously discussed is connected to a tubing string and lowered into the casing wellbore. A description of the procedure used to retrieve the prior art bridge plug can be found in U.S. Pat. No. 4,648,446, column 7, beginning at line 53, and continuing through column 9 line 10.
However, oil and gas operations are increasingly relying on either coiled tubing, wireline or electric line service to perform work previously done by drill pipe or production tubing. One of the reasons for increased reliance on coil tubing, electric line, and wireline is the less expensive cost and ease of operations of utilizing these methods. Also, horizontal wells are being drilled increasingly, and traditional "rigid" workstrings such as drill pipe have certain limitation, as will be understood and appreciated by those skilled in the art. However, the prior art does not provide for the retrieving of the bridge plugs or other downhole apparatus' except by utilizing a rigid workstring in which rotation can be imparted from the surface to the downhole tool.